Transcript Water and Development: The Importance of Irrigation in

Water and Development: The
Importance of Irrigation in
Developing Countries
Karina Schoengold and David
Zilberman
The importance of water
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80% of the human body is made up of water.
Water is crucial element of our food and materials
75% of the earth’s surface is covered with water.
only 3%, is fresh.
Only1% of the water is available for human consumption.
Much of this water contain chemicals making it
inappropriate for human consumption.
• We distinguish between water quality and quantity
problems.
• On average we have sufficient water to meet human needs.
The problem is water distribution.
Many do not have access to water
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Percent of Total Population
without Access to Water in
1994
Africa
54
Latin America
& the Caribbean
20
Asia & the Pacific
20
Western Asia
12
Total
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Absolute Number of People
without Access to Water
(in millions)
381
97
627
10
1,115
Water quality concerns -water born diseases
Estimates of Global Morbidity & Mortality of Water-Related Diseases (early 1990s)
Disease
Diarrheal Diseases
Intestinal Helminths
Schistosomiasis
Dracunculiasis
Trachoma
Malaria
Dengue Fever
Poliomyelitis
Trypanosomiasis
Bancroftian Filariasis
Onchocerciasis
Morbidity (episodes/year or
people infecte d)
1,000,000,000
1,500,000,000 (people infecte d)
200,000,000 (people infecte d)
150,000 (in 1996)
150,000,000 (active cases)
400,000,000
1,750,000
114,000
275,000
72,800,000 (people infec ted)
17,700,000 (people infec ted;
270,000 blind)
Mortality (deaths/year)
3,300,000
100,000
200,000
1,500,000
20,000
130,000
40,000 (mortality caused by
blindness)
Water policy concerns-quality
• Water quality concerns in the tropics are not limited to
human health. Contamination of water by arsenic and
mercury in mining activities are major concerns in the
tropical forest. Such contamination is hazardous to the
forest ecosystems and their bio-diversity.
• When the miners are small, informal organizations, the
regulation of toxic material in mining is a difficult non
source point pollution problem. Solutions are difficult to
implement because of the population density, large scale and
weak government.
• Establishing of mobile unit that can track violators and a
legal system to prosecute is a major priority.
. Social Concerns.
• Waterborne diseases. Bad project planning resulted in
spread of malaria and other water born diseases as vector
spread in canal and dams.
• Displacement of native populations. The development of
water projects in the last century has led to the displacement
of 40 – 80 million people. Compensation for these forced
changes has usually been minimal, if it occurs at all.
• International conflicts and water supply. There are 261
rivers that cross international boundaries. The division of
water resources between countries can either be a source of
conflict or a reason for necessary cooperation. 162 treaties
were signed an implemented for cooperative water
management. Some major disputes ar not settled
Heterogeneity of water
• There are differences in water availability within regions-in
Brazil,Mexico, California, Hawaii, Russia, there are regions
of floods and surpluses and deserts.
• Differences in water availability over time matter - at the
same year you may have floods and shortages
• Differences in water quality are crucial- consumption,
farming of various crops and production require minimum
quality.
• Value and use of water dependent on
– location
– Time
– Quality
Different uses of water
• consumptive usage is diversion + consumption of the water
through
– transforming it into water vapor (where it is “lost” to the atmosphere),
– letting it seep into the ground, or
– significantly degrading its quality. For example
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Residential
Industrial
Agricultural
Forestry
• non-consumptive usage. Do not educe water supply and, frequently,
do not degrade water quality. Examples
– Fisheries use water as a medium for fish growth.
– Hydroelectric users extract energy from the water.
– Recreation may involve using water as a medium (example:
swimming) and/or extracting energy from the water (examples: whitewater rafting, surfing)
– Transportation is especially important use of water in the tropics.
Agriculture Values of water vary
• Agricultural value of water r varies between crops and
locations. A relatively small faction of the water (20%)
generates much of the value (more than 70%).
• Crops such as flowers and strawberries can pay more than
$500/AF, cotton can afford paying $40-100/AF and pasture
$30/AF and less.
• Values of water vary by location,land quality and
according to market conditions.
• Industry and residential users are able to afford to pay
much more than agricultural field crops. Their demand is
relatively small (33%) but is continually growing.
Overview of irrigation
irrigated land has increased from 50 mha (million hectares) in 1900 to
267 mha today.
Between 1962 and 1996 the irrigated area in developing countries
increased at 2% annually.
Irrigation has been crucial in meeting the food demand of doubling
world population since WWII.
Irrigation projects have been costly in terms of capital, environmental
degradation& human health.
Design and management of water resources have been flawed. There is
a growing perception of water supply crisis,but we have a water
management crisis.
As population is likely to grow double again, we need to reform water
institutions and policies.
This presentation first assesses water situation and then introduces
direction for reform.
BENEFITS OF IRRIGATION
• Irrigation increases crop yields.- The 17% of land that is
irrigated is producing 40% of the global food
• The value of production of irrigated cropland is about
$625/ha/year ($95/ha/year for rain-fed cropland and
$17.50/ha/year for rangelands).
• Irrigation affects total factor productivity (TFP) beyond the
input value of the water(evanson,pray,Rosegrant).,
• Irrigation allows improve timing and spatial distribution of
water. It allows double cropping, it enables supply
stabilization. It enable production of vegetables and fruits.
• Increases consumer well being& employment & farm
income(net income increase per family in Africa was $150 - $1000)
• The high productivity of agriculture slowed
expansion of deforestation.
Productivity of irrigation
• 1% increase in irrigation increase productivity by .12-.25%.
• But these are marginal effects
• There is a significant heterogeneity within fields-35%
of yield variance is within field
• There is a significant fixed effect of water.
• Irrigation may double or even triple yields,it increase water
availability and controls when and where water is available.
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The high yields of irrigations may reflect climatic effectsdesert areas have higher sun energy and degree days that
with irrigation leads to higher yields
Modern irrigation and pumping modify ranking and values of
land- irrigation technologies is water quality augmenting.
Water as complement to other factors
• Species evolution (distribution and survival) depend on and adjust to
water conditions... Plants have shallower roots when water is
abundant. Water abundance is key to tropical ecosystems. But they
are vulnerable to water shortages.
• Draught is a relative concept-In parts of Florida and Java a week
without drain is a draught
• Water affects the state of other factors. Water movement causes soil
erosion,drown wild life and destroys property. It lead to migration of
species and changes in bio-diversity.
• Water productivity depends on other factors. For example
Climate (degree days)– Soils
– It may be worth while to export water to regions with warm and
dry climate and good soils.
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Water Projects
• Projects modify bodies of water to enhance some aspects of
productivity. They may include
– Navigation projects
– Storage projects
– Flood protection projects
– Hydroelectric project
• Projects may have negative environmental and social effects.
• A correct analysis of net discounted benefits is a useful guide for
project selection. It should account for non market impacts and
uncertainties.
• Project design should consider institutional and non structural
solutions. Redesign of incentives may lead to water savings
preventing a need for a new dam.
• Cost of projects vary. Costs over run reduce the net benefits of
projects. Projects have non market costs as well.
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Water variability and projects in the tropics
Water conditions in the tropics vary- there are deserts in
Brazil and Africa,and desertification is a continuous concern
in both continent. Land and water management projects can
slow these processes. He challenge is cost effective and
environmental sensitive design, leading to efficient and
equitable outcomes.
Projects to improve water flow and reduce water stagnation
are also important to improve transportation and to improve
public health.
A major priority is to eliminate water borne diseases-using
structural solutions (drainage, sanitation),management
activities( pest control) and medical treatment
Flood control projects used for storage and hydro electric
power generation may be very valuable in the Hymmalaya’s
foothills and other regions.
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COSTS OF IRRIGATION Capital cost 1
COSTS OF IRRIGATION Capital cost 1
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• The capital costs of water projects
have been
underestimated.
• A recent study of 81 dams found that the average cost
overrun was 56%.
• The cost of irrigation has increased substantially since the
1970s.
• Irrigation costs now average $480,000 per square km.
Cost varies by location - the capital cost in China is
$150,000 per square km, while the costs in Africa capital
costs are $1,000,000-2,000,000 per square km.
• Mexico's irrigated area has actually declined since 1985
due to lack of capita
Other costs of projects
Environmental cost
Habitat destruction
Blocking migration of native species
• Increased emissions of greenhouse gases.
• Increased salinity levels in freshwater supplies
• Water logging and salinization of land– Cost 11Billion annually
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20% of the irrigated land worldwide is affected by salinity
– 1.5 million hectares are taken out of production each year as a result of high
salinity levels in the soil.
• Decreased levels of sediment and nutrients in water-Nile
Cost of variability are reduced through storage
and trading
• The uncertainty and variability of water conditions are major sources of
concern.
• The cost of adjustment to random climatic and water conditions can be
reduced by institutional changes-increase in water trading, structural
changes-expansion of storage facilities. And schemes such as
conjunctive use. The optimal strategy choice depends on cost vs
benefits.
• The gain from trade can increase as trading possibility expand.
Expanding water trading may entail:
– Investment in expanded conveyance facilities
– Reducing constraints on trading
• BUT Trading may cause third party effects that have to be taken into
account in design of system of trading
Virtual water
• Value of water vary by location. Defining a water shortage
as a situation where water per capita is below a certain
level is not always useful when a region with minimal
water can use it productively and generate resources to
buy cheap water intensive crops.
• For example, an acre foot of water used in flower
production is equivalent in the value of productivity to 3040acre feet used in wheat.
• Measure of water shortages should combine water
availability and productivity. Water constraints are less
binding as trade opportunities expand.
Water Rights and water Markets
• When population is scarce and water abundant-thjere is open access to
water.
• Riparian rights emerge in regions bordering bodies of water. Users are
entitle to use water adjoin to their land but not to divert water.
• Prior Appropriation is a Queuing system allowing diversion of water
where diversion right are determined according to
– First in time first in line
– Use it or lose it
• PA was designed to induce investment in diversion .But PA does not
provide incentives for water conservation.
• Transferable Rights in water lead to trading and investment in
conservation. Trading design has to be adjusted mitigate negative third
party effects. Transition to Trading may not be worth while if gains are
smaller than the transition costs.
water trading issues
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Transferable rights-annual (rent) and/or permanent (sale)
Sale by government.
In vs out of the basin.
Sale of effective vs applied water.
Compensation to third party
Active vs passive trading
Options to buy/sell
Chile/California/Columbia/
Improved Water Pricing Systems
• In most countries, the revenues received fall far short of the
costs of water without attempt to recover the initial capital
cost
• Recovery of operation and maintenance costs ranges from a
low of 20-30 percent in India and Pakistan to a high of close
to 75 percent in Madagascar
• The most common pricing systems are per-hectare fees
• Per acre fees may vary by season and crop.
• Brazil combines hook up fee with volumetric fee.
• Volumetric inaccurate
• Subsidies of 25%-50% are common
Overuse of Groundwater
Resources
• . Tube-well use in India increased by more than 100-fold between
1960 and 1985
• As much as 8 percent of , food crops grow on farms that use
groundwater faster than the aquifers are replenished
• Groundwater levels have been dropping at 25-30 cm per year. At
depths below 15 meters, tubewells will not function, and a well must
be abandoned.
• The percentage of land where the water table is below 10 meters has
increased from 3 percent to 46 percent between 1973 and 1994.
Ground water management
• Ground water is a complement and substitute to surface water. It may
replace surface water during draught period and be a permanent source
of irrigation water.
• Conjunctive use When ground water is used as a reserve- it is
accumulated during wet years and pumped during dry.
• Permanent pumping is sustainable if pumping is equal to
replenishment.
• Ground water is a common pool resource and may be overused.
Without regulation we might have the tragedy of the commons. Users
should be charged extra for the cost their pumping impose on the
inventory.
• Water and energy subsidies in India and other countries lead to
depletion of ground water aquifers.
Improve ground water management
• India increased pumping by 300% since 1951-86
• Farmers should pay user fee and not be subsidized, either
directly ( through lower water prices)or through subsidized
energy
• Tiered pricing may address poor
• Monitoring is needed-may need regional ground water
authorities.
Water quality: Point and non point pollution
• Agricultural and municipal activities contaminate buddies of
water.Water quality policies distinguishes between
• Source point pollution when the pollution can be monitored and
regulated through financial incentive or direct control.
• Non Point sources which can not be linked to specific pollution, but
are engaged in polluting activities that can be regulated. For example,
government may ban certain waste management practices or establish,
require or subsidize best management practices. Producers may be
penalized or subsidized not based on their pollution but on activities
correlated with pollution.
• Monitoring and enforcement of environmental regulations are
difficult. In many cases the parties affected are very powerful, or very
poor and political will to implement water quality rules is not there.
Water Governance institutions
• There are economics of scale in implementing water diversion and
mining projects. Some are executed and financed by government
agencies. There is also large scope for collective action among private
parties in cooperating to manage and develop water resources.
• Water user associations (or water districts) are being established to
have better cooperation and local representation in developing water
and other natural resources. These organizations are collectively
obtain resources needed for investment and establish and enforce rules
that lead to socially beneficial water and resource management,.
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Such organizations may be responsible to water distribution and
control of non point source pollution.
Inefficiencies in micro-level water management
• Farmer selection of crops and irrigation technologies
affect water use.
• Conservation technologies increase water use
efficiency but require higher per acre cost
• There is 6% adoption of sprinkler and 1% adoption
of drip.
• There are low tech “drip” like technologies
• Low pricing of water is not justifying adoption
• Efficient Pricing of water and drainage will lea to
aoption
Actions to Improve Efficiency of Irrigation
Efficient investment in irrigation projects
– Capital subsides and under-costing the environment lead to
oversized projects
– Not all capacity needs to be used in start of project-over capacity is
needed to deal with uncertainty
– Learning is crucial-delay is worth while-invest when it is optimal
not at first moment when NPV is positive
– Project desgn should include institutions for allocation
– Consider water logging cost and drainage in project design
• Trade and the Concept of “Virtual Water”-forget self relianceuse water for best outcome build storage and trade.
Use of Non-Traditional Water Sources
The world’s 7500 desalting plants can produce
0.1% of the world’s water use. Price of desalinated
water is between $.70-$1.00 per M3.
Reclaimed water may be produced at a cost of 30 to 40
cents per cubic meter., Partially reclaimed water is
used in production of industrial crops such as cotton.
For cotton and certain vegetables, yield levels can be
maintained if high quality water is used early in the
life of a plant and more saline water is applied
towards the end of the season.
IMPROVED CONVEYANCE AND THE
ALLOCATION OF WATER.
• Poor management of irrigation systems leads to
conveyance losses of up to 50 percent
• The social benefit of canal maintenance is greater
than the private benefit. Ignoring these leads to
under investment in canal maintenance, resulting in
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shorter canal systems than optimal
– over-application of water upstream
• Water systems run by a water user associations are
more efficient and better maintained
(Madagaskar,india,China).WUA tax members and
improve distribution and pricing.
Lessons of water resource management
• Water storage matters. The storage facilities enabled agricultural and
other systems to survive severe draughts in many parts of the world.
• Ground water aquifers are valuable reserves. Pumping new wells
increased supply availability and reduce draught costs.
• Conservation makes a difference, Adoption of conservation technologies
and more precise use of resources enabled water system to survive
variability and shortages.
• Crisis trigger change Draught or flood situations were behind some of
the main water reforms in recent years.
• A mixed portfolio of policies is most desirable. Solutions to complex
water problem involve combining structural changes with new
technologies, education and incentives.
Example:California’s trading during drought
• During the 1987-91 draught California (which shunned
water trading) introduced a trading schemes - the water bank.
• The water bank demonstrated the power of trading to reduce
adjustment to shortages. Productivity of water in California
varies across locations, trading allowed water to be used
wherever they have the highest value.
• Buyers and sellers gain from trading. The water bank enable
to sustain many of the perennial crops and provided owners
of water rights who engage in relatively low return activity
to earn higher incomes from water sale.
• The gains from trading is greater in periods of higher
scarcities Climatic and storage variability cause the value of
water to fluctuate, and value of water in the west side may
vary from $5 to $200 per AF.
• Trading was introduced in Chile, India, China and other
regions.
Conclusions
• Need more impact assessment of irrigation and more
econometric studies of performance.
• Irrigation crucial to productivity-some systems are not
sustainable because of over pumping
• There is much potential to increase water productivity
through incentives
• A priority is to increase trading within regions and to
improve maintenance-through institutional changes
• Irrigation technologies and improvement in varieties are
another sources of improved water productivity in
agriculture.
• Water management is a major challenge-cost benefit needed
to improve investment choice and integrate agriculture and
environment and urban water use. Main challenge is
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Refernces
David Zilberman, Ujjayant Chakravorty, and Farhed Shah, “Efficient Management of
Water in Agriculture,” Decentralization and Coordination of Water Resource
Management, ed., Douglas D. Parker and Yacov Tsur (Boston: Kluwer Academic
Publishers, 1997), Chapter 22. As part of the book series, Natural Resource
Management and Policy, Ariel Dinar and David Zilberman, editors.International Water
Management Institute (2001) home page:
http://www.cgiar.org/iwmi/home/wsmap.htm
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K. William Easter, Mark W. Rosegrant and Ariel Dinar, "Formal and Informal Markets
for Water: Institutions, performance, and Constraints," The World Bank Research
Observer, 14:1, pp. 99-116.
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Richards, Alan (2001) “Coping with Water Scarcity: The Governance Challenge” Center
for Global, International and Regional Studies Working Paper. University of California,
Santa Cruz. http://www2.ucsc.edu/globalinterns/wp/wp2001-4.pdf